Method and apparatus for producing a rotationally symmetric component

ABSTRACT

The present invention relates to a method and an apparatus for producing rotationally symmetric components by means of rolling. For producing a rotationally symmetric component having a profile without any bevels from a blank, the present invention suggests that an annular blank should be deformed into a profiled annular component in a first step by means of rolling between a first inner roll and a first outer roll in a diameter-enlarging mode until the radial growth is limited due to the fact that the profiled annular component comes into contact with at least one additional outer roll. In a second step, the profiled annular component is deformed in a profiling mode between a second inner roll and at least one of said outer rolls on its inner and/or outer circumferential surface(s).

[0001] The present invention relates to a method and an apparatus for producing a rotationally symmetric component by means of rolling. The present invention relates in particular to a method and an apparatus for producing a synchronizer sleeve for the gearbox of a motor vehicle.

[0002] There are two kinds of ring rolling: these are radial ring rolling on the one hand, and metal spinning on the other. In the case of radial ring rolling, an annular blank is used as a starting product and deformed between a rotating outer roll and a mandrel arranged on the inner side or an inner roll. When the gap between the mandrel or the inner roll and the outer roll is reduced in size, a tangential flow of material occurs, which leads to a radial growth of the ring. A blank, which can be produced at a comparatively moderate price, is in this way deformed by said rolling into an annular component having a large diameter. In the case of ring rolling, the inner circumferential surface or the outer circumferential surface can be profiled. It is also possible to carry out profiling at both circumferential surfaces in combination. In this case, however, the problem arises that the blank has to be positioned between a profiled outer and a profiled inner roll with the necessary accuracy and that it has to be retained in this position. Especially when the rolling process is started, the danger exists that the blank migrates in the axial direction relative to the rolls. Hence, the profile cannot be formed at the desired location, or it can only be formed with insufficient accuracy.

[0003] Metal spinning means that an annular blank is deformed between a plurality of rolls arranged on the outer circumferential surface. In this case, an external profile can be formed on the blank. These profiles can be produced without the bevels which are typical of ring rolling. In other words, 90° groove recesses are possible in the case of metal spinning.

[0004] Starting from this prior art, it is the object of the present invention to provide a method and an apparatus for producing a rotationally symmetric component, especially a synchronizer sleeve for a motor-vehicle gearbox, said method and apparatus enlarging the diameter of the blank used and being simultaneously able to produce profiles without any bevels (90° recesses).

[0005] For the solution of this task, the present invention provides a method having the features of claim 1. The apparatus according to the present invention is disclosed in claim 10.

[0006] Preferred further developments result from the dependent claims 2 to 9 for the method and 11 to 14 for the apparatus.

[0007] In accordance with the method according to the present invention, the annular blank is first deformed into a profiled annular component by means of ring rolling between a first inner roll and a first outer roll in a diameter-enlarging mode. This profiled annular component is provided on the outer circumferential surface and/or on the inner circumferential surface thereof with a profile. This first step of the method according to the present invention is stopped, when, due to radial growth, the profiled annular component comes into contact with at least one additional outer roll. Said one or said plurality of outer rolls as well as said first outer roll are arranged relative to one another in such a way that the portions of the individual rolls which are in contact with the profiled annular component during the rolling process are located on a common circular path. In a second step of the method according to the present invention, the profiled annular component is deformed on the outer circumferential surface thereof in a profiling mode by at least one of the outer rolls which effectively limit the radial growth at the end of the first step. Also on the inner circumferential surface thereof, the profiled annular component is deformed in a profiling mode without any radial growth in said second step so that the production of profiles without any bevels (e.g. a 90° groove recess) is made possible. By means of the method according to the present invention, a finished rotationally symmetric component, which is profiled both on its inner circumferential surface and on its outer circumferential surface, can be produced by means of rolling alone. It follows that, by means of the method according to the present invention, the final contour of the component can be produced, with simultaneous work hardening of the inner and outer circumferential surfaces produced by means of rolling, especially cold rolling.

[0008] In the following, the present invention will be explained in detail on the basis of an embodiment in connection with the drawings, in which:

[0009]FIG. 1 shows a blank prior to the first method step;

[0010]FIG. 2 shows a profiled annular component produced by deforming the blank, which is shown in FIG. 1, at the end of the first method step, and

[0011]FIG. 3 shows a synchronizer sleeve for a gearbox which has been produced by further deforming the profiled annular component shown in FIG. 2, after the end of the second step.

[0012] In FIG. 1 a blank is shown, which has cylindrical inner and outer circumferential surfaces 1 a, 1 b. Reference numeral 2 stands for a first outer roll, and reference numeral 3 stands for a first inner roll. Whereas the first inner roll 3 has a cylindrical profile in the case of the embodiment shown, the first outer roll 2 has a profiled outer circumferential surface with an inwardly tapering recess having a bottom 2 a which extends in the axial direction of the roll 2 and from which a projection 2 b having a rectangular cross-section projects radially outwards. The projection 2 b extends such that its respective outer surfaces extend at right angles to and parallel to the axis of rotation of said first outer roll 2.

[0013] By means of ring rolling between the first outer roll 2 and the second outer roll, the blank 1 shown in FIG. 1 is deformed into a profiled annular component 4 of the type shown in FIG. 2. The enveloping surface of the profiled annular component 4, which comprises the outer contour of said profiled annular component 4, corresponds to the contour of the recess, without the projection 2 b, formed on the outer circumferential surface of the first outer roll. The profiled annular component 4 has an outwardly opening groove 4 b the cross-section of which increases in size in the radial direction and the groove bottom of which is formed by being brought into contact with the end face of the projection 2 b during the rolling process. The outwardly broadening cross-sectional geometry of the groove 4 b is obtained due to the material flow during the rolling process. The material pressed radially outwards is not able to flow onto the lateral surfaces of the projection 2 b in planar contact therewith. On the contrary, the material of the blank 1 is deformed radially outwards during the ring rolling process, but it is able to flow in the axial direction only to a very limited extent.

[0014] When the blank 1 shown in FIG. 1 is subjected to ring rolling so as to form the profiled annular component 4 shown in FIG. 2, only the first outer roll 2 and the first inner roll 3 are in contact with the respective circumferential surfaces 1 a, 1 b of the blank 1 at the beginning. During the ring rolling process, the blank 1 grows radially outwards until a point is reached at which additional outer rolls, which are arranged outside of the blank 1 and which are not shown here, come into contact with the outer circumferential surface of the profiled annular component 4. At the end of the first method step, the finished component to be produced by means of rolling, in this case a synchronizer sleeve 6, is defined as far as its contour comprising the enveloping surface is concerned.

[0015] At the end of the first method step, the first inner roll 3 can be replaced by a second inner profiled roll 5—if the contour of the component in question should necessitate this. In FIG. 3, this second inner roll 5 is shown as a profiled roll, i.e. it is provided with a convex projection 5 a in the case of the embodiment shown.

[0016] In the second method step, this second inner roll 5 is pressed against the inner circumferential surface 4 a of the profiled annular component 4 and moved continuously radially outwards so as to form on said inner circumferential surface 1 a of the profiled annular component 4 an inwardly opening groove 4 c. Since a growth of the ring in the radial direction is no longer possible due to the rolls applied, the material displaced by the second inner roll 5 flows into the free space defined between the groove 4 b and the projection 2 b, until the contour of the groove 4 b corresponds to that of the projection 2 b. At the end of the deforming process, the first outer roll 2 and the second inner roll 5 enclose a hollow space corresponding to the cross-sectional profile of the synchronizer sleeve produced.

[0017] In the second step, a plurality of, preferably three outer rolls 2 are in contact with the outer circumferential surface of the profiled annular component 4, each of said rolls being displaced relative to the next by an angle of 120°. The contours of the outer circumferential surfaces of these rolls are preferably identical. The outer rolls act continuously on the outer contour of the profiled annular component 4 and prevent a radial growth of the profiled annular component in this way. The enveloping surface of the profiled annular component 4 shown in FIG. 2 is therefore identical with that of the synchronizer sleeve 6 shown in FIG. 3.

[0018] Finally, the synchronizer sleeve 6 produced in this way is released, e.g. in that one of the outer rolls 2 is displaced from its position, and removed from the apparatus.

[0019] In the second method step, a possible axial flow of the material can be limited by guard check plates or by fixed, alternatively also advancable axial rolls. When seen in relation to the circumference of the profiled annular component 4, these axial rolls can be arranged such that they are distributed between the respective outer rolls 2. List of Reference Numerals 1 blank 2 first outer roll 2a bottom 2b projection 3 first inner roll 4 profiled annular component 4b groove (on the outer side) 4c groove (on the inner side) 5 second inner roll 6 synchronizer sleeve 

1. A method of producing a rotationally symmetric component, in particular a synchronizer sleeve for a motor-vehicle gearbox, wherein an annular blank is deformed into a profiled annular component in a first step by means of ring rolling between a first inner roll and a first outer roll in a diameter-enlarging mode until the radial growth is limited due to the fact that the profiled annular component comes into contact with at least one additional outer roll, and wherein in a second step the profiled annular component is deformed in a profiling mode between a second inner roll and at least one of said outer rolls on its inner and/or outer circumferential surface(s).
 2. A method according to claim 1, characterized in that, in said second step, the radial growth of the ring is limited by the outer rolls.
 3. A method according to claim 1 or 2, characterized in that, in said second step, the first inner roll is used as a second inner roll.
 4. A method according to one of the preceding claims, characterized in that, in said first step, a roll having a cylindrical rolling surface is used for forming a profiled annular component having a cylindrical inner surface.
 5. A method according to one of the preceding claims, characterized in that, between said first step and said second step, the first inner roll is replaced by a second inner roll whose profile is different from that of the first inner roll.
 6. A method according to one of the preceding claims, characterized in that, in said first step, the blank is deformed in a profiling mode on the outer circumferential surface thereof.
 7. A method according to one of the preceding claims, characterized in that, in said second step, the profiled annular component is deformed while maintaining the outer contour comprising the enveloping surface of the profiled annular component.
 8. A method according to one of the preceding claims used for producing a synchronizer sleeve of a gearbox, characterized in that, in said first step, a first groove opening towards the outer circumferential surface is formed and that, in said second step, a second groove opening towards the inner circumferential surface is formed, and that the first groove is reduced in size by the volume displaced in this way.
 9. A method according to one of the preceding claims, characterized in that, in said first step, a first groove is formed, which has a cross-section that broadens in the radial direction and which, in said second step, is deformed into a groove whose lateral surfaces extend substantially at right angles to the central longitudinal axis of the profiled annular component.
 10. An apparatus for producing a rotationally symmetric component, in particular a synchronizer sleeve for a gearbox, by deforming a blank, comprising a plurality of outer profiled rolls and two inner rolls which can selectively be caused to act on the inner side of the component opposite an outer roll, said first inner roll having a flat and said second inner roll a profiled circumferential surface.
 11. An apparatus according to claim 10, characterized in that the outer profiled rolls have identically implemented circumferential surfaces.
 12. An apparatus according to claim 10 or 11, characterized in that at least one of said outer rolls is movably supported.
 13. An apparatus according to one of the claims 11-12, characterized in that at least one of said outer rolls, preferably a roll which is arranged in a stationary manner, is driven.
 14. An apparatus according to one of the claims 10 to 13, characterized by at least one axial roll which is adapted to be advanced towards the end face of said component and a counterroll which is associated with said axial roll. 